The feature of the shape of palm print is easy to capture, because it is information on the surface of human body. However, the individual authentication by use of the palm print is considered susceptible to imposture. On the other hand, the vein's vascular pattern, which is the information inside the human body, has the advantage of being secure against imposture. For this reason, it is widely utilized in the method for individual identification. More recently, in order to raise the accuracy of the biometric authentication, there is proposed a method for individual authentication by a plurality of biometric components (multifactor authentication) which is in combination with other biometrics authentication, based on the authentication using vein pattern.
For example, Japanese Unexamined Patent Application Publication No. 2010-152706 (hereinafter referred to as patent document 1) proposes a two-factor authentication which combines the vein pattern on the palm with the shape of the palm profile. Japanese Unexamined Patent Application Publication No. 2009-175810 (hereinafter referred to as patent document 2) discloses an authentication technique using the shape of palm veins and the shape of finger veins. Further in Japanese Unexamined Patent Application Publication No. 2006-120026 (hereinafter referred to as patent Document 3), an individual authentication device is disclosed which extracts a plurality of vein patterns from a finger or a hand in a single operation.
On the other hand, in order to acquire the vein pattern using such techniques, the subject's finger or hand is irradiated with near-infrared rays, and the image which is formed under this near-infrared rays is photographed. The near-infrared rays easily penetrate through a living-body, and has a high absorbability in the vein portion, thus enabling the acquisition of the image showing the vein pattern by a camera that can take photograph under the near-infrared rays. However, the above-mentioned technique has an inconvenience that a dedicated device is indispensable which is capable of providing the emission and photography under near-infrared rays.
For solving the above-described problems, the present inventor proposed a technology in PCT International Publication Application Publication No. WO 2012/014300, in which two visible light cameras are oppositely arranged to photograph the pattern of veins on the back of a hand and the shape of the palm print simultaneously to provide individual authentication.